Blender game - explosion type motion
You can use the manipulate center points option for this. It works best with a pivot set to the 3D cursor so select the center cube, and Shift+S>Cursor to selected to send the cursor there. Then hit . to set the pivot to the 3D cursor.



Enable the manipulate center points option by clicking the arrow with the dots over it. Now simply scale the all the objects to send them further away. (S